1. Field of the Invention
The present invention relates to microprocessor-based computer bus interface controllers, and more particularly relates to timing control of signals therein.
2. Background Art
The Personal Computer Memory Card International Association ("PCMCIA") interface allows a variety of external I/O and memory cards to be attached to a microcomputer by way of a specially configured socket. The signal timings for the PCMCIA interface are defined to predetermined values having a predetermined range. Timings for bus signals are typically derived utilizing a readily available dock, such as the system clock. However, modern microcomputers have system clocks that run at frequencies that can change, for example under selection control by a user. This presents a problem relating to the maintenance of the aforementioned defined PCMCIA timings.
The present invention provides a novel apparatus that provides an elegant solution to the aforementioned problem, permitting the maintenance of optimal bus signal timings, even if the system dock's frequency changes.